In spite of successful experience with large diameter arterial prostheses in the aortic region, development of reliable substitutes for vascular reconstruction of coronary, femoral, carotid and iliac arteries remains elusive. Small diameter synthetic grafts fail primarily due to the formation of blood clots, fracture of the neointima and excessive proliferation of collagen and smooth muscle cells at the anastomotic lines. Although there has been much research on small diameter grafts, little data documents the relationship between surface properties of the graft near the anastomoses and blood and tissue responses in that region. In specific, the proposed study is intended to further delineate the role of pores in the anastomotic space with regard to thrombus formation, proliferation of cells and the formation of an organized neointima. We will fabricate grafts with one end porous and the other one smooth. These grafts will be implanted into the femoral circulation of a canine model for four weeks. The tissue responses at the anastomotic lines will be compared by measuring the thickness of the neointima and characterizing fibroblasts, smooth muscle cells and endothelial cells. The long term goal of this research is the development of a viable small diameter vascular graft and appropriate surgical techniques that give rise to long term patency rates.